Mucosal histochemistry in secretory otitis.

Mucosal biopsies were taken from 20 ears with secretory otitis media (glue ear) and histochemical stainings were made for comparison with data obtained from biochemical analysis of the fluids. Acid phosphatase, lactate dehydrogenase (LD), and malate dehydrogenase (MD), the activity of which in the ear fluids was 20 to 30 times higher than in serum, were found to appear as strong precipitates in the middle ear epithelium, particularly in the top layer. Alkaline phosphatase activity was only exceptionally seen in the epithelium but appeared in the capillaries and histiocytes. Nonspecific esterase appeared irregularly in the epithelium and regularly in histiocytes. The latter two had lower activities in ear fluids than in serum. Epithelial secretory cells and subepithelial glands and cysts showed strong alcian blue (AB)-positive staining. Positive material appeared also in the cytoplasm of the epithelial cells and in the intercellular substance. Distinct PAS-positive staining appeared in the columnar epithelium and particularly in the free mucus on top of the epithelium but was less promounced in the glandular structures and absent from the cysts.